dovecot - Jun 2009 - Managesieve fails to retrieve scripts > 8kB on Dovecot 1.1.16

After some help with debugging tips on #dovecot, I have established that
a sieve script on Dovecot 1.1.16 has to be less than 8kB in order to be
retrieved by a managesieve client.  I have been using managesieve for
about 6 months over as many 1.1.n versions of dovecot as have been
around during that time and hit this problem when I upgraded to Dovecot
1.1.16.  I have gone back to Dovecot 1.1.15 and can once again manage my
9kB sieve script remotely.

Symptoms were that managesieve login was OK but instead of displaying my
sieve script, the script editing window was empty.  After 30 seconds the
client gave me a timeout message.  If I entered a small script in the
empty client edit window and saved it, the new, small script was saved
to the server and became active.  I could then successfully retrieve and
edit that small script.

I tried hacking a few lines at a time out of my 9kB script (locally on
the server).  When it was down to 8.4KB I still couldn't get it through
managesieve.  The next hack took it down to 7.7kB and I could get that
through managesieve.  So, I'm guessing there's a magic 8192 number in
there somewhere - perhaps a buffer?

 Server
  dovecot 1.1.16
  dovecot-sieve 1.1.6
  dovecot-managesieve 0.10.6
  FreeBSD 7.2

 Client
  Thunderbird 2.0.21
  Sieve 0.1.6

A special thanks to all who write this stuff: it's great!

-- 
John Marshall
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John Marshall schreef:
> After some help with debugging tips on #dovecot, I have established that
> a sieve script on Dovecot 1.1.16 has to be less than 8kB in order to be
> retrieved by a managesieve client.  I have been using managesieve for
> about 6 months over as many 1.1.n versions of dovecot as have been
> around during that time and hit this problem when I upgraded to Dovecot
> 1.1.16.  I have gone back to Dovecot 1.1.15 and can once again manage my
> 9kB sieve script remotely.
> 
> Symptoms were that managesieve login was OK but instead of displaying my
> sieve script, the script editing window was empty.  After 30 seconds the
> client gave me a timeout message.  If I entered a small script in the
> empty client edit window and saved it, the new, small script was saved
> to the server and became active.  I could then successfully retrieve and
> edit that small script.
> 
> I tried hacking a few lines at a time out of my 9kB script (locally on
> the server).  When it was down to 8.4KB I still couldn't get it through
> managesieve.  The next hack took it down to 7.7kB and I could get that
> through managesieve.  So, I'm guessing there's a magic 8192 number
in
> there somewhere - perhaps a buffer?
> 
I cannot reproduce your problem at my end with the given information. A 
14 kb script is no problem here (tried with large comment and repetitive 
if statements). I am using the same client you have.

A few questions:

1) What is your exact config (i.e. dovecot -n)
2) Do the logs say anything? Segfault perhaps (signal 11) ?
3) Could you provide (an anonymized version of) the script you are 
trying to upload? (Make sure the version you send me is problematic as well)

If it truly does hang at some point, you could use the strace tool to 
get an idea what it the managesieve daemon doing at that time. If you 
are not using TLS, you can use the ngrep tool to capture the TCP traffic 
between client and server. That may also prove useful.

Regards,

-- 
Stephan Bosch
stephan at rename-it.nl

On Fri, 2009-06-19 at 21:17 +1000, John Marshall wrote:
> After some help with debugging tips on #dovecot, I have established that
> a sieve script on Dovecot 1.1.16 has to be less than 8kB in order to be
> retrieved by a managesieve client.  I have been using managesieve for
> about 6 months over as many 1.1.n versions of dovecot as have been
> around during that time and hit this problem when I upgraded to Dovecot
> 1.1.16.  I have gone back to Dovecot 1.1.15 and can once again manage my
> 9kB sieve script remotely.
I suppose it's because of this patch:

diff -r 6604f9980a93 -r 7f6aaca52639 src/lib/ostream-file.c
--- a/src/lib/ostream-file.c    Sun May 17 22:06:11 2009 -0400
+++ b/src/lib/ostream-file.c    Mon Jun 01 01:46:52 2009 -0400
@@ -631,6 +631,10 @@
        } while ((uoff_t)ret != send_size);
 
        i_stream_seek(instream, v_offset);
+       if (ret == 0) {
+               /* we should be at EOF, verify it by reading instream */
+               (void)i_stream_read(instream);
+       }
        return ret < 0 ? -1 : (off_t)(instream->v_offset - start_offset);
 }
 
But that code is supposed to fix it, not break it..
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